Multicast data packet processing method, and apparatus

ABSTRACT

A multicast data packet processing method performed by an intermediate node of a multicast tree includes: receiving a first Bit Index Explicit Replication (BIER) packet including a first label; obtaining, according to the first label, a second label corresponding to a multicast tree including the intermediate node; and obtaining a second BIER packet according to the second label and the first BIER packet, and sending the second BIER packet which includes the second label.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.17/009,640, filed on Sep. 1, 2020, which is a continuation ofInternational Application No. PCT/CN2019/075317, filed on Feb. 18, 2019,which claims priority to Chinese Patent Application No. 201810175653.1,filed on Mar. 2, 2018. All of the aforementioned applications are herebyincorporated by reference in their entireties.

TECHNICAL FIELD

Embodiments of this application relate to the field of communicationstechnologies, and in particular, to a multicast data packet processingmethod, and an apparatus.

BACKGROUND

In a multicast technology, a specific multicast address is used totransmit a multicast data packet to a host set corresponding to amulticast group according to a maximum delivery principle. A basicmethod of the multicast technology is as follows: A source host sendsonly one multicast data packet, and a destination address of themulticast data packet is a multicast group address. Each receiver in themulticast group may receive one multicast data packet. The multicasttechnology implements point-to-multipoint (P2MP) data transmission in aninternet protocol (IP) network, effectively reducing network bandwidthand network load.

A P2MP-based BIER technology is one of BIER technologies. In a multicastnetwork to which the P2MP-based BIER technology is applied, a multicasttree includes a P2MP tree in which a specified edge node is used as aroot and another edge node is used as a leaf. The specific edge node isan edge node that is close to a multicast source and that cancommunicate with the multicast source. The another edge node is an edgenode in the multicast network other than the specific edge node. A bitposition may be allocated to each edge node used as a leaf, and the bitposition may be used to uniquely identify the edge node of the multicasttree that is used as a leaf. Each edge node used as a leaf sends the bitposition of the edge node to the root node of the multicast tree byusing a tree building protocol, for example, a protocol independentmulticast (PIM) protocol, multipoint extensions for a label distributionprotocol (mLDP), or resource reservation protocol-traffic engineering(RSVP-TE). Each node of the multicast tree may learn of an edge nodethat is used as a leaf and that corresponds to each bit position. Theroot node may encapsulate a bit string into a multicast data packet tobe sent to an edge node used as a leaf. A bit position in the bit stringindicates a destination edge node at which the multicast data packet isto arrive. After receiving the multicast data packet including the bitstring, a node of the multicast tree forwards the multicast data packetbased on the bit string included in the multicast data packet, so thatthe multicast data packet is sent to the edge node that is used as aleaf and that is identified by the bit string.

To deploy the BIER technology in the multicast network, a device in themulticast network needs to be capable of identifying and processing abit string in a BIER header. Currently, the device in the network needsto be upgraded to support the BIER technology. Consequently, the BIERtechnology has relatively high deployment costs and relatively greatdeployment difficulty.

SUMMARY

Embodiments of this application provide a multicast data packetprocessing method, and an apparatus, to resolve a prior-art problem thata BIER technology has relatively high deployment costs and relativelygreat deployment difficulty in a multicast network.

To achieve the foregoing objective, the following technical solutionsare used in the embodiments of this application.

According to a first aspect, a multicast data packet processing methodis provided, applied to a P2MP-based BIER multicast tree, where anintermediate node of the multicast tree supports to use P2MP to forwarda BIER packet, and the method includes: receiving, by the intermediatenode, a first multicast data packet, where a BIER header of the firstmulticast data packet includes a first label; obtaining, by theintermediate node, a first forwarding entry based on the first label,where the first forwarding entry includes the first label, a firstidentifier, and a second identifier, the first identifier is used toidentify the multicast tree, and the second identifier is used toinstruct to perform P2MP forwarding on the packet; obtaining, by theintermediate node, a second forwarding entry based on the firstidentifier, where the second forwarding entry includes the firstidentifier and a second label; and obtaining, by the intermediate node,a second multicast data packet based on the second identifier, thesecond forwarding entry, and the first multicast data packet, andsending the second multicast data packet, where the second multicastdata packet includes the second label. That the intermediate nodesupports to use P2MP to forward the BIER packet may be understood asthat the intermediate node does not support to process data in the BIERheader other than a BIER label, and the intermediate node uses P2MP toforward the BIER packet. Herein, processing performed on a bit stringincludes: reading the bit string, an operation (an AND operation), and asubsequent forwarding action. The forwarding action is determining,based on an AND result, whether to perform a forwarding operation for anext hop. In addition, the intermediate node may further play a role ofa multicast leaf. To be specific, the intermediate node may send amulticast data packet to a next-level node of the intermediate node, andmay further send a multicast IP packet to a locally connected device.

In the foregoing technical solution, when the intermediate node cannotidentify and process a bit string in the BIER header, but supports touse P2MP to forward the BIER packet, when receiving the BIER packet, theintermediate node may read only the BIER label, does not need to read oranalyze data in the BIER header other than the BIER label, and uses P2MPto forward the BIER packet, so that the BIER technology can be deployedwithout upgrading hardware of a node, and deployment costs anddeployment difficulty of the BIER technology are reduced.

In a possible implementation of the first aspect, the second forwardingentry further includes an outbound interface, and the obtaining, by theintermediate node, a second multicast data packet based on the secondidentifier, the second forwarding entry, and the first multicast datapacket, and sending the second multicast data packet includes:replacing, by the intermediate node based on the second identifier, thefirst label included in the first multicast data packet with the secondlabel, to obtain the second multicast data packet; and sending, by theintermediate node, the second multicast data packet through the outboundinterface. Optionally, the outbound interface is determined by theintermediate node based on an identifier of a downstream node of theintermediate node, and is not necessarily determined based on aninterface for receiving information from the downstream node of theintermediate node. In the foregoing possible implementation, whenperforming forwarding processing on the first multicast data packet, theintermediate node may replace the first label included in the firstmulticast data packet only with the second label, to obtain the secondmulticast data packet, and send the second multicast data packet throughthe outbound interface, thereby simplifying a BIER packet processingmanner, so that the intermediate node can use P2MP to forward the BIERpacket, and the deployment costs and difficulty of the BIER technologyare further reduced.

In a possible implementation of the first aspect, before the obtaining,by the intermediate node, a first forwarding entry based on the firstlabel, the method further includes: generating, by the intermediatenode, the first forwarding entry based on first configurationinformation, the first label, and the first identifier, where the firstconfiguration information is used to indicate that the intermediate nodeuses P2MP to forward the BIER packet, and the second identifier is anidentifier obtained based on the first configuration information.Optionally, the intermediate node may generate the second identifierbased on the first configuration information, or search a correspondencetable based on the first configuration information, to obtain the secondidentifier. In the foregoing possible implementation, the intermediatenode may obtain the second identifier based on a correspondingconfiguration, and generate the first forwarding entry, so that whenforwarding the BIER packet, the intermediate node can use P2MP toforward the BIER packet.

In a possible implementation of the first aspect, the second forwardingentry further includes a third identifier and an outbound interface, thethird identifier is used to instruct to delete data in the BIER headerother than a BIER label, and the obtaining, by the intermediate node, asecond multicast data packet based on the second identifier, the secondforwarding entry, and the first multicast data packet, and sending thesecond multicast data packet includes: replacing, by the intermediatenode based on the second identifier, the first label included in thefirst multicast data packet with the second label, to obtain alabel-replaced first multicast data packet; deleting, by theintermediate node based on the third identifier, data in a BIER headerof the label-replaced first multicast data packet other than the secondlabel, to obtain the second multicast data packet; and sending, by theintermediate node, the second multicast data packet through the outboundinterface. Optionally, the outbound interface is determined by theintermediate node based on an identifier of a downstream node of theintermediate node, and is not necessarily determined based on aninterface for receiving information from the downstream node of theintermediate node. In the foregoing possible implementation, when thedownstream node of the intermediate node does not support to delete theBIER label from the BIER header, the intermediate node may furtherdelete the data in the BIER header other than the BIER label, andforward the BIER packet, so that deployment costs and difficulty of theBIER technology can be further reduced.

In a possible implementation of the first aspect, before the obtaining,by the intermediate node, a second forwarding entry based on the firstidentifier, the method further includes: receiving, by the intermediatenode, the second label and second configuration information that aresent by a downstream node in the multicast tree, where the secondconfiguration information is used to indicate that the downstream nodedoes not support to delete the data in the BIER header other than theBIER label; and generating, by the intermediate node, the secondforwarding entry based on the second label and the second configurationinformation, where the third identifier is an identifier obtained basedon the second configuration information. The downstream node in themulticast tree may be a next-hop node of the intermediate node on apacket transmission path including the intermediate node and a specificleaf node. In the foregoing possible implementation, the intermediatenode may obtain the second identifier based on a correspondingconfiguration, and generate the second forwarding entry, so that whenforwarding the BIER packet, the intermediate node can delete the data inthe BIER header other than the BIER label.

According to a first aspect, a multicast data packet processing methodis provided, applied to a P2MP-based BIER multicast tree, where anintermediate node of the multicast tree supports to delete data in aBIER header other than a BIER label, and the method includes: receiving,by the intermediate node, a first multicast data packet, where a BIERheader of the first multicast data packet includes a first label;obtaining, by the intermediate node, a first forwarding entry based onthe first label, where the first forwarding entry includes the firstlabel and a first identifier, and the first identifier is used toidentify the multicast tree; obtaining, by the intermediate node, asecond forwarding entry based on the first identifier, where the secondforwarding entry includes the first identifier, a second identifier, anda second label, and the second identifier is used to instruct to deletethe data in the BIER header other than the BIER label; and obtaining, bythe intermediate node, a second multicast data packet based on thesecond forwarding entry and the first multicast data packet, and sendingthe second multicast data packet, where the second multicast data packetincludes the second label.

In the foregoing technical solution, when a downstream node of theintermediate node does not support to delete the data in the BIER headerother than the BIER label, when forwarding a multicast data packet, theintermediate node may delete data in a BIER header of the multicast datapacket other than a BIER label, so that the downstream node of theintermediate node can implement processing or forwarding on the receivedmulticast data packet. In this way, a BIER packet can be forwardedwithout upgrading hardware of a node, and deployment costs anddifficulty of a BIER technology are further reduced.

In a possible implementation of the second aspect, the second forwardingentry further includes an outbound interface, and the obtaining, by theintermediate node, a second multicast data packet based on the secondforwarding entry and the first multicast data packet, and sending thesecond multicast data packet includes: deleting, by the intermediatenode based on the second identifier, data in the BIER header of thefirst multicast data packet other than the first label, to obtain adata-deleted first multicast data packet; replacing, by the intermediatenode, the first label included in the data-deleted first multicast datapacket with the second label, to obtain the second multicast datapacket; and sending, by the intermediate node, the second multicast datapacket through the outbound interface. Optionally, the outboundinterface is determined by the intermediate node based on an identifierof a downstream node of the intermediate node, and is not necessarilydetermined based on an interface for receiving information from thedownstream node of the intermediate node. In the foregoing possibleimplementation, when performing forwarding processing on the firstmulticast data packet, the intermediate node may replace the first labelincluded in the first multicast data packet only with the second label,to obtain the second multicast data packet, and send the secondmulticast data packet through the outbound interface, therebysimplifying a BIER packet processing manner, so that the intermediatenode can use P2MP to forward a packet that carries a BIER label, anddeployment costs and difficulty of a BIER technology are furtherreduced.

In a possible implementation of the second aspect, before the obtaining,by the intermediate node, a second forwarding entry based on the firstidentifier, the method further includes: receiving, by the intermediatenode, the second label and configuration information that are sent by adownstream node in the multicast tree, where the configurationinformation is used to indicate that the downstream node does notsupport to delete the data in the BIER header other than the BIER label;and generating, by the intermediate node, the second forwarding entrybased on the second label and the configuration information, where thesecond identifier is an identifier obtained based on the configurationinformation. The downstream node in the multicast tree may be a next-hopnode of the intermediate node on a packet transmission path includingthe intermediate node and a specific leaf node. In the foregoingpossible implementation, the intermediate node may obtain the secondidentifier based on a corresponding configuration, and generate thesecond forwarding entry, so that when forwarding the BIER packet, theintermediate node can delete the data in the BIER header other than theBIER label.

According to a third aspect, a multicast data packet processing methodis provided, and applied to a P2MP-based BIER multicast tree, where themulticast tree includes a leaf node, the leaf node does not support toprocess a bit string in a BIER header, and the method includes:receiving a second multicast data packet, where a BIER header of thesecond multicast data packet includes only a second BIER label;obtaining a third forwarding entry based on a multicast tree identifier,where the third forwarding entry includes a fourth identifier, and thefourth identifier is used to instruct to delete the BIER label; deletingthe second BIER label from the second multicast data packet based on thefourth identifier, to obtain a multicast IP packet; and sending themulticast IP packet to a local outbound interface.

In a possible implementation of the third aspect, the method furtherincludes: generating the third forwarding entry based on preconfiguredlabel deletion instruction information and a first identifier, where thefourth identifier is an identifier obtained based on configurationinformation, and the label deletion instruction information is used toinstruct the leaf node to delete the BIER label when the leaf nodelocally forwards a multicast data packet.

According to a fourth aspect, a forwarding device is provided. Theforwarding device is an intermediate node applied to a P2MP-based BIERmulticast tree, the forwarding device supports to use P2MP to forward aBIER packet, and the forwarding device may implement a function of themulticast data packet processing method provided in any one of the firstaspect to the possible implementations of the first aspect. The functionmay be implemented by hardware, or may be implemented by hardwareexecuting corresponding software. The hardware or the software includesone or more units corresponding to the foregoing function. For example,the forwarding device may include a receiving unit, an obtaining unit,and a sending unit. The forwarding device may further include ageneration unit.

In a possible implementation of the fourth aspect, a structure of theforwarding device includes a processor, a memory, a communicationsinterface, and a bus, and the processor, the memory, and thecommunications interface are connected by using the bus. The memory isconfigured to store program code, and when the program code is executedby the processor, the forwarding device is enabled to perform steps inthe multicast data packet processing method provided in any one of thefirst aspect to the possible implementations of the first aspect.

According to a fifth aspect, a forwarding device is provided. Theforwarding device is an intermediate node applied to a P2MP-based BIERmulticast tree, the forwarding device supports to delete data in a BIERheader other than a BIER label, and the forwarding device may implementa function of the multicast data packet processing method provided inany one of the second aspect to the possible implementations of thesecond aspect. The function may be implemented by hardware, or may beimplemented by hardware executing corresponding software. The hardwareor the software includes one or more units corresponding to theforegoing function. For example, the forwarding device may include areceiving unit, an obtaining unit, and a sending unit. The forwardingdevice may further include a generation unit.

In a possible implementation of the fifth aspect, a structure of theforwarding device includes a processor, a memory, a communicationsinterface, and a bus, and the processor, the memory, and thecommunications interface are connected by using the bus. The memory isconfigured to store program code, and when the program code is executedby the processor, the forwarding device is enabled to perform steps inthe multicast data packet processing method provided in any one of thesecond aspect to the possible implementations of the second aspect.

According to a sixth aspect, a forwarding device is provided. Theforwarding device is a leaf node applied to a P2MP-based BIER multicasttree, the forwarding device does not support to process a bit string ina BIER header, and the forwarding device may implement a function of themulticast data packet processing method provided in any one of the thirdaspect to the possible implementations of the third aspect. The functionmay be implemented by hardware, or may be implemented by hardwareexecuting corresponding software. The hardware or the software includesone or more units corresponding to the foregoing function. For example,the forwarding device may include a receiving unit, a processing unit,and a sending unit.

In a possible implementation of the sixth aspect, a structure of theforwarding device includes a processor, a memory, a communicationsinterface, and a bus, and the processor, the memory, and thecommunications interface are connected by using the bus. The memory isconfigured to store program code, and when the program code is executedby the processor, the forwarding device is enabled to perform steps inthe multicast data packet processing method provided in any one of thethird aspect to the possible implementations of the third aspect.

According to another aspect of this application, a computer readablestorage medium is provided. The computer readable storage medium storesan instruction. When the instruction is run on a computer, the computeris enabled to perform the multicast data packet processing methodprovided in any one of the first aspect or the possible implementationsof the first aspect.

According to another aspect of this application, a computer readablestorage medium is provided. The computer readable storage medium storesan instruction. When the instruction is run on a computer, the computeris enabled to perform the multicast data packet processing methodprovided in any one of the second aspect or the possible implementationsof the second aspect.

According to another aspect of this application, a computer programproduct including an instruction is provided. When the computer programproduct is run on a computer, the computer is enabled to perform themulticast data packet processing method according to any one of thefirst aspect or the possible implementations of the first aspect.

According to another aspect of this application, a computer programproduct including an instruction is provided. When the computer programproduct is run on a computer, the computer is enabled to perform themulticast data packet processing method according to any one of thesecond aspect or the possible implementations of the second aspect.

It may be understood that any one of the above provided apparatus,computer storage medium, or computer program product for the multicastdata packet processing method is configured to perform the correspondingmethod provided above. Therefore, for beneficial effects that can beachieved by the apparatus, the computer storage medium, or the computerprogram product, refer to beneficial effects in the corresponding methodprovided above. Details are not described herein again.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic structural diagram of a multicast tree accordingto an embodiment of this application;

FIG. 2 is a schematic structural diagram of a BIER header according toan embodiment of this application;

FIG. 3 is a schematic flowchart of the 1^(st) multicast data packetprocessing method according to an embodiment of this application;

FIG. 4 is a schematic flowchart of the 2^(nd) multicast data packetprocessing method according to an embodiment of this application;

FIG. 5 is a schematic flowchart of the 3^(rd) multicast data packetprocessing method according to an embodiment of this application;

FIG. 6 is a schematic flowchart of the 4^(th) multicast data packetprocessing method according to an embodiment of this application;

FIG. 7 is a schematic diagram of forwarding a first BIER packetaccording to an embodiment of this application;

FIG. 8 is a schematic diagram of forwarding a second BIER packetaccording to an embodiment of this application;

FIG. 9 is a schematic diagram of forwarding a third BIER packetaccording to an embodiment of this application;

FIG. 10 is a schematic diagram of forwarding a fourth BIER packetaccording to an embodiment of this application;

FIG. 11 is a schematic diagram of forwarding a fifth BIER packetaccording to an embodiment of this application;

FIG. 12 is a schematic structural diagram of a first forwarding deviceused as an intermediate node according to an embodiment of thisapplication;

FIG. 13 is a schematic structural diagram of a second forwarding deviceused as an intermediate node according to an embodiment of thisapplication;

FIG. 14 is a schematic structural diagram of a third forwarding deviceused as an intermediate node according to an embodiment of thisapplication; and

FIG. 15 is a schematic structural diagram of a fourth forwarding deviceused as an intermediate node according to an embodiment of thisapplication.

DESCRIPTION OF EMBODIMENTS

FIG. 1 is a schematic structural diagram of a multicast tree accordingto an embodiment of this application. The multicast tree may include aroot node, an intermediate node, and a leaf node. The intermediate nodemay be a node other than an edge node, for example, a node B and a nodeC in FIG. 1 . Edge nodes may include the root node and the leaf node. Anode A is a root node. A node D, a node E, and a node F are leaf nodes.When the node E used as a leaf node is further used as an intermediatenode, a transmission path between the node E and the node C may replacea transmission path between the node B and the node C in FIG. 1 , togenerate another multicast tree. When the node E used as a leaf node isfurther used as an intermediate node, the node E is referred to as a budnode. A structure of the multicast tree shown in FIG. 1 is merely anexample, and does not constitute a limitation on this application.

A procedure of forwarding a multicast data packet includes: A root nodeof a multicast tree receives a multicast data packet sent by a multicastsource, and the root node sends the multicast data packet to a leaf nodeof the multicast tree. The root node forwards the multicast data packetto a downstream node. A downstream node of a node is a next-hop node ofthe node on a transmission path in a direction from the root node to theleaf node in the multicast tree. If the downstream node of the root nodeis an intermediate node, the intermediate node sends the multicast datapacket to the leaf node of the multicast tree by using a downstream nodeof the intermediate node. After receiving the multicast data packet, theleaf node sends, through a local port, the multicast data packet to ahost connected to the local port. If the multicast tree has a bud node,the bud node sends a replicated multicast data packet through a localport in addition to sending the multicast data packet to a downstreamnode of the bud node. In the multicast tree shown in FIG. 1 , the node Asends, to the downstream node B of the node A, a multicast data packetthat comes from a multicast source. The node B replicates the multicastdata packet, and separately sends the multicast data packet to thedownstream nodes E and C of the node B. The node C replicates themulticast data packet, and separately sends the multicast data packet tothe downstream nodes F and D of the node C. The node F and the node Dmay separately send the multicast data packet through respective localports. When the node E is a bud node, the node E may replicate themulticast data packet, and separately send the multicast data packetthrough a local port of the node E and a port through which the node Ecan communicate with the downstream node C.

In the multicast tree shown in FIG. 1 , a bit string that can identifyfour edge nodes is used as an example to describe a relationship betweena bit string, a bit position, and an edge node. A bit positioncorresponding to the node D is 1, a bit position corresponding to thenode E is 2, a bit position corresponding to the node F is 3, and a bitposition corresponding to the node A is 4. When the node D is an edgenode that receives a multicast data packet, a bit string correspondingto the multicast data packet may be represented as 0001. When the node Eis an edge node that receives a multicast data packet, a bit stringcorresponding to the multicast data packet may be represented as 0010.When the node F is an edge node that receives a multicast data packet, abit string corresponding to the multicast data packet may be representedas 0100. When the node F and the node D are data nodes that receive amulticast data packet, a bit string corresponding to the multicast datapacket may be represented as 0101. In a process of building themulticast tree, the nodes D, E, and F notify respective bit positions torespective upstream nodes by using a tree building protocol. An upstreamnode of a node is a previous-hop node of the node on the transmissionpath in the direction from the root node to the leaf node in themulticast tree. After receiving notifications from the nodes D, E, andF, the node A obtains and stores the bit positions of the nodes D, E,and F. After receiving a multicast data packet from the multicastsource, the node A determines, based on information about the multicastsource and information about a multicast group, that the multicast datapacket needs to be sent to the nodes E and F. The node A learns, basedon the bit positions of the node E and the node F, that a parameterbitstring is 0110. The node A obtains a BIER packet based on theparameter bitstring and the multicast data packet. The BIER packetincludes a BIER header and the multicast data packet. A parameterbitstring included in the BIER header is 0110. The node A sends the BIERpacket to the node B.

As shown in FIG. 2 , the BIER header includes a 32-bit BIER label,64-bit other fields, and a parameter bitstring. The parameter BIER-labelincludes a label value and other information about the label. Theparameter BIER-label may be used to determine a length of the parameterbitstring. The label value may occupy the first 20 bits of the parameterBIER-label. The other information about the label may occupy the last 12bits of the parameter BIER-label. The length of the parameter bitstringmay be 64 bits, 128 bits, or 256 bits. The length of the parameterbitstring may be alternatively set to another value, and the length ofthe parameter bitstring is not described herein by using examples one byone. For the other fields, refer to corresponding content in RFC8296.

Before forwarding a multicast data packet by using a P2MP-based BIERtechnology, each node included in a multicast tree builds a forwardingentry by using a control plane. After building the forwarding entry,each node included in the multicast tree sends the multicast data packeton a forwarding plane based on the forwarding entry. The followingseparately describes, by using different embodiments, a process ofbuilding the forwarding entry and a process of forwarding the multicastdata packet.

In a forwarding entry building method provided in an embodiment of thisapplication, a forwarding entry of each node in a multicast tree may bebuilt hop by hop in a direction from a leaf node to a root node. Thefollowing describes in detail a forwarding entry of each node and aprocess of building the forwarding entry.

(1) Related descriptions of forwarding entries of the root node, anintermediate node, and the leaf node

a. Forwarding entry of the root node

The root node supports to use P2MP to forward a BIER packet, and theroot node can identify and process a bit string in a BIER header.Forwarding entries of the root node include the following two types: afirst forwarding entry and a second forwarding entry. The firstforwarding entry may be represented as a mapping from a forwardingequivalence class (FEC) to a next hop label forwarding entry (NHLFE)(FEC to NHLFE, FTN). The second forwarding entry may be represented asBIER_NHLFE. The forwarding entry FTN includes a multicast source (S), amulticast group (G), a multicast tree identifier (treeid), and a bitstring. For example, the forwarding entry FTN is represented as (S, G,treeid, bitstring). The parameter treeid included in the forwardingentry FTN is an identifier obtained by the root node based on a P2MP IDfrom a downstream node of the root node in a process of building themulticast tree. The parameter treeid included in the forwarding entryFTN is used to uniquely identify the multicast tree on the root nodelocally. The root node may search the forwarding entry FTN based on (S,G) in a received multicast data packet, to obtain the parameter treeidand the parameter bitstring. A leaf node that receives the multicastdata packet is determined based on a bit position in the parameterbitstring in the forwarding entry FTN. In this embodiment of thisapplication, that the P2MP ID is used as an identifier used in a treebuilding protocol is used as a specific example to describe a method forobtaining a forwarding entry by each node of the multicast tree. TheP2MP ID may be correspondingly replaced according to a used treebuilding protocol. For example, if the tree building protocol isRSVP-TE, the identifier used in the tree building protocol is a P2MPsession. If the tree building protocol is mLDP, the identifier used inthe tree building protocol is a P2MP FEC. If the tree building protocolis PIM, the identifier used in the tree building protocol is multicastsource and group information used to build the multicast tree. Themulticast source and group information may be represented as (S, G). Inthis embodiment of this application, that the P2MP ID comes from thedownstream node is used as an example for description. The P2MP ID mayalternatively be obtained by using an upstream node. In this embodimentof this application, a method for obtaining the P2MP ID from theupstream node is not described again.

The forwarding entry BIER_NHLFE includes the parameter treeid, anoutbound interface (outinterface), an outbound label (outlabel), and aforwarding bit mask (F-BM). For example, the forwarding entry BIER_NHLFEis represented as (treeid, outinterface, outlabel, F-BM). The root nodemay obtain, based on the parameter treeid in the forwarding entry FTN,the forwarding entry BIER_NHLFE including the parameter treeid. The rootnode may obtain the parameter outinterface, the parameter outlabel, andthe parameter F-BM based on the obtained forwarding entry BIER_NHLFE.The parameter F-BM is a parameter obtained by the root node based on abit position that is notified of by the leaf node that needs to receivethe multicast data packet corresponding to (S, G). When the root nodesends a BIER packet to the leaf node corresponding to the parameterbitstring, the root node may perform a logical AND operation on theparameter bitstring included in the BIER header and the parameter F-BMin the forwarding entry BIER_NHLFE. If a result of the AND operation isnot 0, the root node sends the BIER packet through the outboundinterface corresponding to the parameter outinterface in the forwardingentry BIER_NHLFE. A BIER label in the BIER packet sent through theoutbound interface corresponding to the parameter outinterface isencapsulated as the parameter outlabel. If the result of the ANDoperation is 0, the root node does not send the BIER packet to theoutbound interface corresponding to the parameter outinterface in theforwarding entry BIER_NHLFE.

b. Forwarding entry of the intermediate node

(i) The intermediate node supports a BIER technology, and at least onedownstream node of the intermediate node does not support to delete datain a BIER header other than a BIER label. To be distinguished from namesof the first forwarding entry and the second forwarding entry,forwarding entries of the intermediate node include the following twotypes: a third forwarding entry and a fourth forwarding entry. The thirdforwarding entry may be represented as a BIER incoming label mapping(BIER_ILM). The fourth forwarding entry may be represented asBIER_NHLFE. A type of a parameter included in the fourth forwardingentry is the same as a type of a parameter included in the forwardingentry BIER_NHLFE of the root node. Details are not described hereinagain. The third forwarding entry and the fourth forwarding entry mayalso have other names. This is not specifically limited herein.

The forwarding entry BIER_ILM includes an incoming label (inlabel), aparameter treeid, a bit string length (bitstringlen), and a first flagbit. The first flag bit may be represented as flag=checkbitstring. Theforwarding entry BIER_ILM may be represented as (inlabel, treeid,bitstringlen, flag=checkbitstring). The parameter inlabel is a label ofthe intermediate node that is sent by the intermediate node to the rootnode. The parameter treeid in the forwarding entry BIER_ILM is anidentifier obtained by the intermediate node based on a P2MP ID from adownstream node of the intermediate node in a process of building themulticast tree. The parameter treeid included in the forwarding entryBIER_ILM is used to uniquely identify the multicast tree on theintermediate node locally. The intermediate node uses, as the parameterinlabel, a BIER label in a received BIER packet, to obtain theforwarding entry BIER_ILM. The intermediate node may obtain theparameter treeid, the parameter bitstringlen, and the parameterflag=checkbitstring from the forwarding entry BIER_ILM. The parameterbitstringlen is used to identify a length of a parameter bitstring in aBIER header. Both a length of a parameter bitstring in a packet carryingthe BIER header and a length of the parameter F-BM in the fourthforwarding entry are bitstringlen. The parameter flag=checkbitstringinstructs to identify and process the parameter bitstring in the BIERheader. For example, an AND operation is performed on the identifiedparameter bitstring in the BIER header and the parameter F-BM in thefourth forwarding entry, to determine whether to continue to send, tothe downstream node, the packet carrying the BIER header. The parameterbitstringlen is notified of by the downstream node in a process in whicha control plane generates an entry. In this embodiment of thisapplication, a manner in which the parameter bitstringlen is sent by adownstream node to an upstream node is used as an example to describe amethod for generating a forwarding entry by the node of the multicasttree. When a tree building protocol is RSVP-TE, the parameterbitstringlen may come from a path message sent by the upstream node tothe downstream node, or may come from a reservation message (RESVmessage) sent by the downstream node to the upstream node. A manner ofobtaining the bitstringlen is not limited in this embodiment of thisapplication.

The forwarding entry BIER_NHLFE includes the parameter treeid, theparameter outinterface, the parameter outlabel, the parameter F-BM, anda second flag bit. The second flag bit may be represented asflag=popBIERexcluding. The parameter flag=popBIERexcluding instructs topop out data in the BIER header other than the BIER label. Theforwarding entry BIER_NHLFE may be represented as (treeid, outinterface,outlabel, F-BM, flag=popBIERexcluding). For meanings of the parameteroutinterface, the parameter outlabel, and the parameter F-BM, refer tocorresponding content in the second forwarding entry. For a meaning ofthe parameter treeid, refer to a meaning of the parameter treeid in thethird forwarding entry. The intermediate node may learn, based onconfiguration information sent by the downstream node, that at least onedownstream node does not support to delete the data in the BIER headerother than the BIER label. The at least one downstream node may supportto read the BIER label. The configuration information is used toindicate that the downstream node does not support to delete the data inthe BIER header other than the BIER label. The intermediate node may addthe parameter flag=popBIERexcluding based on the configurationinformation when generating a forwarding entry BIER_NHLFE correspondingto the at least one downstream node. Correspondingly, the intermediatenode may obtain the parameter treeid based on the forwarding entryBIER_ILM. The intermediate node may obtain, based on the parametertreeid included in the forwarding entry BIER_ILM, the forwarding entryBIER_NHLFE including the parameter flag=popBIERexcluding. When a resultof an AND operation performed on the parameter bitstring and theparameter F-BM in the forwarding entry BIER_NHLFE is not 0, theintermediate node deletes the data in the BIER header other than theBIER label, and replaces the BIER label in the BIER header with theoutlabel. The intermediate node may subsequently send, with reference tothe manner used by the root node, a packet that carries a P2MP label butdoes not carry other parameters in the BIER header after the label isreplaced. The intermediate node may further configure, in a commonmethod for a downstream node that supports the BIER technology, aforwarding entry BIER_NHLFE corresponding to the downstream node.Details are not described herein again.

(ii) The intermediate node supports a BIER technology, and plays a roleof a leaf node. At least one downstream node of the intermediate nodedoes not support to delete data in a BIER header other than a BIERlabel. In addition to the third forwarding entry and the fourthforwarding entry in (i), forwarding entries of the intermediate nodefurther include a fifth forwarding entry and a sixth forwarding entry.The fifth forwarding entry may be represented as BIER_NHLFE_Leaf. Thesixth forwarding entry may be represented as a multicast forwardinginformation base (MFIB). The forwarding entry BIER_NHLFE_Leaf includes aparameter treeid and a third flag bit. The third flag bit may berepresented as flag=popBIERincluding. The parameterflag=popBIERincluding instructs to delete a BIER header from a BIERpacket. Deleting the BIER header from the BIER packet is deleting, fromthe BIER packet, data including a length bitstringlen plus 12 bytesstarting from a BIER label. The forwardin entry BIER_NHLFE_Leaf isrepresented as (treeid, flag=popBIERincluding). The intermediate nodesearches for a local MFIB by using a multicast data packet whose BIERheader is deleted, and sends the multicast data packet to a localoutbound interface based on the found MFIB. The MFIB may be expressed as(S, G, localmcastId). The parameter localmcastId is used to locate anentry MFIB_LocalLeaf. The intermediate node that plays the role of aleaf further uses the parameter localmcastId to search for the entryMFIB_LocalLeaf, to obtain the local outbound interface of theintermediate node that plays the role of a leaf. The entryMFIB_LocalLeaf may be represented as (localmcastld, outinterface).

(iii) The intermediate node supports to use P2MP to perform forwarding,and the intermediate node does not support to identify or process aparameter bitstring in a BIER header. Identifying and processing theparameter bitstring in the BIER header includes: reading the parameterbitstring in the BIER header, and using the parameter bitstring todetermine whether to forward, to a downstream node, a packet carryingthe BIER header. Forwarding entries of the intermediate node include thefollowing two types: a seventh forwarding entry and an eighth forwardingentry. The seventh forwarding entry may be represented as P2MP_ILM. Theeighth forwarding entry may be represented as P2MP_NHLFE.

The forwarding entry P2MP_ILM includes a parameter inlabel, a parametertreeid, and a fourth flag bit. For the parameter inlabel and theparameter treeid, refer to corresponding content in (i) and (ii). Thefourth flag bit may be represented as flag=P2MP. The parameter flag=P2MPis used to instruct to use P2MP for forwarding. The forwarding entryP2MP_ILM may be represented as (inlabel, treeid, flag=P2MP). The fourthflag bit may be set by the intermediate node based on performance of theintermediate node in a process of generating a forwarding entry. Theperformance of the intermediate node includes: supporting P2MPforwarding and not supporting to identify and process the parameterbitstring in the BIER header. The forwarding entry P2MP_NHLFE includes aparameter treeid, a parameter outinterface, and a parameter outlabel.For meanings of the parameter treeid, the parameter outinterface, andthe parameter outlabel, refer to corresponding content in (i) and (ii).The forwarding entry P2MP_NHLFE may be represented as (treeid,outinterface, outlabel). Using P2MP for forwarding indicates thatforwarding is to be implemented based on a label carried in ato-be-forwarded packet and a corresponding forwarding entry. Thecorresponding forwarding entry may be the forwarding entry P2MP_NHLFEdetermined based on the parameter treeid in the forwarding entryP2MP_ILM.

(iiii) The intermediate node supports to use P2MP for forwarding. Theintermediate node does not support to identify and process a parameterbitstring in a BIER header, and at least one downstream node of theintermediate node does not support to delete data in the BIER headerother than a BIER label. Forwarding entries of the intermediate nodeinclude the following several types: the seventh forwarding entry in(iii) and a ninth forwarding entry. The ninth forwarding entry may beobtained by adding the second flag bit to the eighth forwarding entry in(iii). To be specific, the ninth forwarding entry may be represented as(treeid, outinterface, outlabel, flag=popBIERexcluding). For samecontent in the ninth forwarding entry and the eighth forwarding entry,refer to (iii). For the second flag bit, refer to corresponding contentin (i).

When the intermediate node corresponding to (iiii) further plays a roleof a leaf node, forwarding entries of the intermediate node may furtherinclude the fifth forwarding entry and the sixth forwarding entry in(ii) in addition to the seventh forwarding entry and the ninthforwarding entry.

Any one of the foregoing flag bits is set by the intermediate node basedon corresponding configuration information carried in a notificationsent by the downstream node of the intermediate node. A representationmanner of any flag bit is not limited to the foregoing representationmanner.

c. Forwarding entry of the leaf node

(i) The leaf node supports to delete a BIER header, and forwardingentries of the leaf node may include the following several types:BIER_ILM represented as (inlabel, treeid, bitstringlen,flag=checkbitstring) and BIER_NHLFE_Leaf represented as (treeid,flag=popBIERincluding). Alternatively, a forwarding entry of the leafnode may be BIER_ILM represented as (inlabel, treeid, bitstringlen,flag=popBIERincluding). The parameter inlabel is a label of the leafnode. For content of the parameter bitstringlen and the parameterflag=checkbitstring, refer to corresponding content on the intermediatenode. The parameter flag=popBIERincluding instructs to delete a BIERheader from a BIER packet. For specific content, refer to correspondingcontent on the intermediate node.

(ii) The leaf node does not support to delete data in a BIER headerother than a BIER label, and forwarding entries of the leaf node mayinclude P2MP_ILM represented as (inlabel, treeid) and P2MP_NHLFE_Leafrepresented as (treeid, flag=poplabel). Alternatively, a forwardingentry of the leaf node may be P2MP_ILM represented as (inlabel, treeid,flag=poplabel). The parameter flag=poplabel instructs to delete a labelfrom a packet, and the label may be a BIER label or a P2MP label.

(iii) If the leaf node plays a role of an intermediate node, for aforwarding entry of the leaf node that plays the role of an intermediatenode, refer to the forwarding entry of the intermediate node that playsthe role of a leaf node in b.

It should be noted that a parameter treeid in the forwarding entry ofthe leaf node may be an identifier obtained by the leaf node based on aP2MP ID in a process of building the multicast tree. The parametertreeid is used to uniquely identify the multicast tree on the leaf nodelocally.

(2) Related descriptions of building forwarding entries of the rootnode, an intermediate node, and the leaf node

The leaf node of the multicast tree learns of a P2MP identifier(identifier, ID) corresponding to the multicast tree. The P2MP IDincludes: an IP address of the root node and an identifier of themulticast tree in which the leaf node is located. The identifier of themulticast tree in which the leaf node is located may be an identifierrepresented by using a sequence number. The leaf node of the multicasttree learns of a next-hop node in an upstream direction. As shown inFIG. 1 , a node A is a next-hop node of a node B in an upstreamdirection, the node B is a next-hop node of a node E in the upstreamdirection, a node C is a next-hop node of a node D in the upstreamdirection, and the node B is a next-hop node of the node C in theupstream direction. The leaf node of the multicast tree may learn of abit position corresponding to the leaf node. The node D may send a bitmask (bitmask) whose content is 0001, to notify that a bit position ofthe node D is 1. Likewise, the node E may send a parameter bitmask whosecontent is 0010, to notify that a bit position of the node E is 2. Anode F may send a parameter bitmask whose content is 0100, to notifythat a bit position of the node F is 3. The leaf node of the multicasttree may send a label used to identify the leaf node to an upstream nodeof the leaf node. The leaf node of the multicast tree may further send,to the upstream node of the leaf node, configuration information used toindicate whether the leaf node supports to delete data in a BIER headerother than a BIER label. In this way, the leaf node of the multicasttree may send the parameter bitmask, the P2MP ID, and the label of theleaf node to the next-hop node in the upstream direction of the leafnode. The intermediate node may obtain a corresponding forwarding entryin (1) based on the foregoing information sent by the leaf node. Theleaf node may obtain the corresponding forwarding entry in (1) based onthe configuration information and the label of the leaf node. As shownin FIG. 1 , it is assumed that a label of the node D may be label<byD>,and the node D sends (P2MP ID, label<byD>, bitmask=0001, configurationinformation) to the node C. A label of the node F may be label<byF>, andthe node F sends (P2MP ID, label<byF>, bitmask=0100, configurationinformation) to the node C. A label of the node E may be label<byE>, andthe node E sends (P2MP ID, label<byE>, bitmask=0010, configurationinformation) to the node B. The intermediate node may use label<by node>as a parameter outlabel. The intermediate node obtains a parametertreeid based on the identifier that is of the multicast tree and that isin the P2MP ID. The intermediate node may use the parameter bitmask as aparameter F-BM based on a capability of the intermediate node. Theintermediate node may set a flag based on received configurationinformation.

The intermediate node obtains a corresponding bit string based on aparameter bitmask sent by a downstream node. Specifically, theintermediate node may obtain the corresponding bit string by performingan OR operation on the parameter bitmask from the downstream node. Theintermediate node may send the supported capability, a label of theintermediate node, and the obtained parameter bitstring to the IPaddress that is of the root node and that is included in the P2MP ID.Specifically, a method for sending the supported capability, the labelof the intermediate node, and the obtained parameter bitstring mayinclude: The intermediate node obtains a next-hop node in an upstreamdirection based on an IP address of the root node; and the intermediatenode sends the label of the intermediate node and the obtained parameterbitstring to the next-hop node in the upstream direction. The capabilitysupported by the intermediate node may be sent by using theconfiguration information. For the capability supported by theintermediate node, refer to the corresponding descriptions in (1). Theintermediate node may obtain a forwarding entry related to a parameterinlabel in (1) based on the capability of the intermediate node, theobtained parameter treeid, and the label of the intermediate node. Thelabel of the intermediate node is the parameter inlabel in theforwarding entry of the intermediate node.

For example, as shown in FIG. 1 , a label of the node C may belabel<byC>, and the node C performs an “or” operation on two parametersbitmask from the nodes D and F, to obtain bitmask=0101 obtained afterthe “or” operation. The node C obtains, based on the IP address of theroot node, that a next hop in a direction to the root node is the nodeB. The node C sends information (P2MP ID, label<byC>, bitmask=0101,configuration information) to the node B. The configuration informationsent by the node C is used to indicate a capability of the node C and acapability of a leaf node connected to the node C. The node C may builda corresponding forwarding entry based on label<byC> and informationthat is sent by the nodes D and F. A label of the node B may belabel<byB>. The node B performs an “or” operation on two parametersbitmask from the nodes E and C, to obtain bitmask=0111 obtained afterthe “or” operation. The node B sends (P2MP ID, label<byB>, bitmask=0111)to the node A based on the IP address of the root node. The node B maybuild a corresponding forwarding entry based on label<byB> andinformation that is sent by the nodes E and C.

Related description of building the forwarding entry by the root node:After receiving information sent by a downstream node, the root node maybuild, based on the information sent by the downstream node, theforwarding entry that is of the root node and that is described in (1).For example, as shown in FIG. 1 , the node A obtains a correspondingforwarding entry based on information from the node B, a capability ofthe node A, and a label of the node A.

For specific descriptions of a forwarding entry of a root node, aforwarding entry of an intermediate node, and a forwarding entry of aleaf node that are of a multicast tree in the following embodimentscorresponding to FIG. 3 , FIG. 4 , FIG. 5 , or FIG. 6 , refer tocorresponding content in (1). For a specific manner of generating aforwarding entry by any node of the multicast tree in the followingembodiments corresponding to FIG. 3 , FIG. 4 , FIG. 5 , or FIG. 6 ,refer to corresponding content in (2).

FIG. 3 is a schematic flowchart of a multicast data packet processingmethod according to an embodiment of this application. This method isapplied to a P2MP-based BIER multicast tree. An intermediate node of themulticast tree supports to use P2MP to forward a received packet. Thefollowing describes the method provided in this embodiment of thisapplication with reference to FIG. 3 .

Step 301: The intermediate node receives a first multicast data packet,where a BIER header of the first multicast data packet includes a firstlabel.

If the intermediate node does not support to process data in a BIERheader other than a BIER label, for example, does not support to performidentification processing on a parameter in the BIER header other thanthe BIER label, the intermediate node uses P2MP to forward the receivedpacket. The received packet may be a multicast data packet that carriesthe BIER header or a multicast data packet that does not carry theparameter in the BIER header other than the BIER label. The parameter inthe BIER header other than the BIER label may be a parameter bitstring.The identification processing may include: reading the parameterbitstring, an operation (AND operation), and a subsequent forwardingaction. The forwarding action may be determining, based on an ANDresult, whether to perform a forwarding operation for a next hop.

The first label in the BIER header of the first multicast data packet isa label of the intermediate node. The first multicast data packet may besent by an upstream node of the intermediate node to the intermediatenode. The upstream node may be a root node, or may be an intermediatenode other than the intermediate node. The root node supports toidentify and process the parameter bitstring in the BIER header. Whenthe root node needs to send a multicast data packet to a leaf node inthe multicast tree, the root node may obtain, based on (S, G) and aforwarding entry FTN in the multicast data packet, a parameter treeidand a parameter bitstring that are used as first identifiers. The rootnode finds a forwarding entry BIER_NHLFE (treeid, outinterface,outlabel, F-BM) based on the obtained parameter treeid. The root nodeperforms an AND operation on the parameter bitstring and the parameterF-BM. When a result of the logical AND operation is not 0, the firstmulticast data packet is obtained based on the parameter bitstring andthe parameter outlabel that is used as the first label. The root nodesends the first multicast data packet to an outbound interfaceidentified by the parameter outinterface, to send the first multicastdata packet to the intermediate node.

When the upstream node of the intermediate node is also an intermediatenode, the intermediate node used as the upstream node may have a samecapability as the root node, a BIER packet may be forwarded withreference to the method used by the root node. If the intermediate nodeused as the upstream node does not support to process the data in theBIER header other than the BIER label, the intermediate node used as theupstream node may process the received first multicast data packet inthe following method provided in this embodiment of this application.

Step 302: The intermediate node obtains a first forwarding entry basedon the first label, where the first forwarding entry includes the firstlabel, a first identifier, and a second identifier, the first identifieris used to identify the multicast tree, and the second identifier isused to instruct to perform P2MP forwarding on the packet.

The intermediate node may obtain the first forwarding entry based on thefirst label. The first identifier in the first forwarding entry is usedto identify the multicast tree, and the second identifier is used toinstruct to perform P2MP forwarding on the packet. For example, thefirst identifier may be the parameter treeid included in the forwardingentry of the intermediate node mentioned in the foregoing embodiment.For example, the second identifier may be the parameter flag=P2MPincluded in the forwarding entry of the intermediate node mentioned inthe foregoing embodiment. Correspondingly, the first forwarding entrymay include the forwarding entry P2MP_ILM represented as (inlabel,treeid, flag=P2MP) that is on the intermediate node and that ismentioned in the foregoing embodiment.

Step 303: The intermediate node obtains a second forwarding entry basedon the first identifier, where the second forwarding entry includes thefirst identifier and a second label.

The intermediate node may obtain the second forwarding entry based onthe first identifier. The second label included in the second forwardingentry is a label of a downstream node of the intermediate node that issent by the downstream node. For example, the second forwarding entrymay include a forwarding entry P2MP_NHLFE represented as (treeid,outlabel). The intermediate node may obtain the second forwarding entrybased on the treeid in the forwarding entry P2MP_ILM expressed as(inlabel, treeid, flag=P2MP). The parameter outlabel in the secondforwarding entry may be referred to as the second label. Optionally, thesecond entry may further include the parameter outinterface included inthe forwarding entry P2MP_NHLFE that is on the intermediate node andthat is mentioned in b.

Step 304: The intermediate node obtains a second multicast data packetbased on the second identifier, the second forwarding entry, and thefirst multicast data packet, and sends the second multicast data packet,where the second multicast data packet includes the second label.

When the intermediate node obtains the second identifier, the secondforwarding entry, and the first multicast data packet, the intermediatenode determines, based on the second identifier, to perform P2MPforwarding. After determining to perform P2MP forwarding, theintermediate node may not need to perform identification processing on areceived parameter in the BIER header other than the BIER label. Theintermediate node processes the first multicast data packet based on thesecond label in the second forwarding entry, to obtain the secondmulticast data packet. The BIER label in the BIER header of the secondmulticast data packet is the second label. The intermediate node maysend the second multicast data packet to the downstream node of theintermediate node.

When the downstream node of the intermediate node supports to delete thedata in the BIER header other than the BIER label or does not support todelete the data in the BIER header other than the BIER label, methodsfor obtaining and sending, by the intermediate node, the second datamulticast packet in step 304 are different. The following separatelydescribes the methods.

In a manner, if the downstream node of the intermediate node supports todelete the data in the BIER header other than the BIER label, the secondforwarding entry may further include an outbound interface. Optionally,the outbound interface may be determined based on an identifier of thedownstream node of the intermediate node, and the outbound interface maybe the same as or different from an interface through which theintermediate node receives information sent by the downstream node ofthe intermediate node. Correspondingly, step 304 may specificallyinclude: The intermediate node replaces the first label in the firstmulticast data packet with the second label in the second forwardingentry based on the second identifier, to obtain the second multicastdata packet; and the intermediate node sends the second multicast datapacket to the downstream node of the intermediate node through theoutbound interface in the second forwarding entry. For example, if thesecond identifier is flag=P2MP, and the second forwarding entry includesa forwarding entry P2MP_NHLFE represented as (treeid, outinterface,outlabel), the intermediate node may replace the BIER label in the BIERheader of the first multicast data packet with the parameter outlabel,to obtain the second multicast data packet, and send the secondmulticast data packet to the downstream node of the second multicastdata packet by using the parameter outinterface. In this case, both thefirst multicast data packet and the second multicast data packet may bepackets carrying the BIER header.

In another manner, when the downstream node of the intermediate nodedoes not support to delete the data in the BIER header other than theBIER label, the second forwarding entry further includes a thirdidentifier and an outbound interface, and the third identifier is usedto instruct to delete the data in the BIER header other than the BIERlabel. Optionally, the outbound interface may alternatively bedetermined based on an identifier of the downstream node of theintermediate node, and the outbound interface may be the same as ordifferent from an interface through which the intermediate node receivesinformation sent by the downstream node of the intermediate node.Correspondingly, step 304 may specifically include: The intermediatenode replaces, based on the second identifier, the first label includedin the first multicast data packet with the second label, to obtain alabel-replaced first multicast data packet; the intermediate nodedeletes, based on the third identifier, data in the BIER header of thelabel-replaced first multicast data packet other than the second labelafter the label is replaced, to obtain the second multicast data packet,to be specific, the second multicast data packet includes only thesecond packet and a multicast IP packet; and the intermediate node sendsthe second multicast data packet through the outbound interface. Forexample, the second identifier is flag=P2MP, the third identifier isflag=popBIERexcluding, and the second forwarding entry includes aforwarding entry P2MP_NHLFE represented as (treeid, outinterface,outlabel, flag=popBIERexcluding). In this case, the intermediate nodemay replace the BIER label in the BIER header of the first multicastdata packet with the parameter outlabel (the second label), to obtainthe label-replaced first multicast data packet, and delete the data inthe BIER header other than the second label based on the parameterflag=popBIERexcluding, to obtain the second multicast data packet. To bespecific, the second multicast data packet includes the second packetand the multicast IP packet. The intermediate node sends the secondmulticast data packet to the downstream node of the intermediate node byusing the parameter outinterface. In this case, the first multicast datapacket may be a packet that carries the BIER header, and the secondmulticast data packet may be a packet that carries a P2MP label but doesnot carry another parameter in the BIER header.

When the downstream node of the intermediate node is a leaf node, theleaf node may receive the second multicast data packet. The leaf nodemay obtain a third forwarding entry based on the first identifier. Thethird forwarding entry includes the first identifier and a fourthidentifier, and the fourth identifier is used to instruct to delete thesecond label. Therefore, the leaf node may delete the second label fromthe second multicast data packet based on the third identifier, toobtain the multicast IP packet. The leaf node reads a source IP and adestination IP (multicast group IP) in an IP header of the multicast IPpacket, finds, through matching, a local multicast forwarding entry,determines a local outbound interface based on the local multicastforwarding entry, and sends the multicast IP packet to the localoutbound interface. For example, the third forwarding entry may includea forwarding entry P2MP_NHLFE_Leaf (treeid, flag=poplabel), theparameter treeid may be the first identifier, and the parameterflag=poplabel may be the fourth identifier. The multicast forwardingentry may include an MFIB (S, G, localmcastld), (S, G) is referred to asmulticast source and group information, and the parameter localmcastldmay be used to indicate the local outbound interface. The parameterflag=poplabel is used to instruct to pop out a label, and the label maybe a BIER label or a P2MP label.

Correspondingly, before the leaf node obtains the third forwarding entrybased on the first identifier, the leaf node may further generate thethird forwarding entry. Specifically, the leaf node may generate thethird forwarding entry based on indication information and the firstidentifier. The indication information is used to instruct the leaf nodeto delete the BIER label when locally forwarding a packet, and thefourth identifier is an identifier obtained based on the indicationinformation.

When the intermediate node is further used as a leaf node, theintermediate node may send the multicast IP packet to the local outboundinterface of the intermediate node according to the foregoing method forprocessing the second multicast data packet by the leaf node. Fordetails, refer to the descriptions of the leaf node. The details are notdescribed in this embodiment of this application.

Further, before the intermediate node processes the first multicast datapacket, the intermediate node may further generate the first forwardingentry and the second forwarding entry that are required for forwardingthe first multicast data packet. Specifically, referring to FIG. 4 ,before the intermediate node obtains the first forwarding entry based onthe first label (namely, step 302), the method may further include step300 a.

Step 300 a: The intermediate node generates a first forwarding entrybased on first configuration information, the first label, and the firstidentifier, where the first configuration information is used toindicate that the intermediate node uses P2MP to forward a BIER packet,and the second identifier is an identifier obtained based on the firstconfiguration information. The second identifier is an identifierobtained based on the first configuration information. A manner ofobtaining the second identifier may include: generating the secondidentifier based on the first configuration information, or searching acorrespondence table based on the first configuration information toobtain the second identifier. When the intermediate node uses P2MP toforward the BIER packet, the first configuration information may beconfigured for the intermediate node, so that the intermediate nodeobtains the second identifier based on the first configurationinformation, and generates the first forwarding entry based on the firstlabel, the first identifier, and the second identifier. For example, theintermediate node may obtain an identifier flag=P2MP based on the firstconfiguration information, and generate the first forwarding entry basedon the first label label<by node 1> (the node 1 represents theintermediate node) and the parameter treeid used as the firstidentifier. The first forwarding entry may be a forwarding entryP2MP_ILM represented as (inlabel, treeid, flag=P2MP). The parameterinlabel is a label of the intermediate node.

Specifically, referring to FIG. 4 , before the intermediate node obtainsthe second forwarding entry based on the first identifier (namely, step303), the method may further include steps 300 b and step 300 c. In FIG.4 , an example in which step 300 a to step 300 c are performed beforestep 301 is used for description.

Step 300 b: The intermediate node receives a second label and secondconfiguration information that are sent by a downstream node in themulticast tree, where the second configuration information is used toindicate that the downstream node does not support to delete the data inthe BIER header other than the BIER label.

When the downstream node of the intermediate node does not support todelete the data in the BIER header, other than the BIER label thedownstream node may send the second configuration information to theintermediate node, and send the second label to the intermediate node.

Step 300 c: The intermediate node generates the second forwarding entrybased on the first identifier, the second label, and the secondconfiguration information, where the third identifier is an identifierobtained based on the second configuration information.

The third identifier is an identifier obtained based on the secondconfiguration information. A manner of obtaining the third identifiermay include: generating the third identifier based on the secondconfiguration information, or searching the correspondence table basedon the second configuration information to obtain the third identifier.When the intermediate node receives the second configurationinformation, the intermediate node may obtain the third identifier basedon the second configuration information, and generate the secondforwarding entry based on the first identifier, the second label, andthe third identifier. For example, the intermediate node may obtain anidentifier flag=popBIERexcluding based on the second configurationinformation, and generate the second forwarding entry based on theparameter treeid used as the first identifier, a label label<by node 2>(the node 2 represents the downstream node of the intermediate node)used as the second label, and the parameter flag=popBIERexcluding usedas the third identifier. The second forwarding entry may be representedas P2MP_NHLFE (treeid, outinterface, outlabel, flag=popBIERexcluding).The parameter outlabel is label<by node2>, namely, a label of thedownstream node of the intermediate node.

In this embodiment of this application, if the intermediate node cannotidentify and process a bit string in the BIER header, but supports touse P2MP to forward the BIER packet, when the intermediate node receivesthe first multicast data packet and obtains the first forwarding entryand the second forwarding entry, the intermediate node may process thefirst multicast data packet based on the second forwarding entry and thesecond identifier that is in the first forwarding entry and that is usedto instruct to perform P2MP forwarding on the packet, to obtain thesecond multicast data packet, and does not need to read or analyze theBIER header of the first multicast data packet during processing, sothat the BIER packet can be forwarded without upgrading hardware of thenode, thereby reducing hardware upgrading costs. In addition, when thedownstream node of the intermediate node does not support to delete thedata in the BIER header other than the BIER label, when forwarding amulticast data packet, the intermediate node may further delete data ina BIER header of the multicast data packet other than a BIER label, sothat the downstream node of the intermediate node can implementprocessing or forwarding on the received multicast data packet. In thisway, the BIER packet can be forwarded without upgrading hardware of thenode, and hardware upgrading costs are further reduced.

FIG. 5 is a schematic flowchart of a multicast data packet processingmethod according to an embodiment of this application. The method isapplied to a P2MP-based BIER multicast tree, and an intermediate node ofthe multicast tree supports to delete data in a BIER header other than aBIER label. Referring to FIG. 5 , the method includes the followingseveral steps.

Step 501: The intermediate node receives a first multicast data packet,where a BIER header of the first multicast data packet includes a firstlabel.

For details, refer to corresponding content in 301 in the embodimentcorresponding to FIG. 4 or FIG. 3 .

Step 502: The intermediate node obtains a first forwarding entry basedon the first label, where the first forwarding entry includes the firstlabel and a first identifier, and the first identifier is used toidentify the multicast tree.

The intermediate node may obtain the first forwarding entry based on thefirst label. The first identifier in the first forwarding entry is usedto identify the multicast tree. For example, the first identifier may bethe parameter treeid in the forwarding entry provided in the foregoingembodiments, the first label is a label of the intermediate node, andthe first forwarding entry may include a forwarding entry P2MP_ILMrepresented as (inlabel, treeid). The parameter inlabel may be a labelof the intermediate node.

Step 503: The intermediate node obtains a second forwarding entry basedon the first identifier, where the second forwarding entry includes thefirst identifier, a second identifier, and a second label, and thesecond identifier is used to instruct to delete the data in the BIERheader other than the BIER label.

The intermediate node may obtain the second forwarding entry based onthe first identifier. The second label included in the second forwardingentry is a label that is allocated and sent by a downstream node of theintermediate node to the intermediate node. For example, the secondforwarding entry may include a forwarding entry P2MP_NHLFE representedas (treeid, outlabel, flag=popBIERexcluding). The intermediate node mayobtain the second forwarding entry based on the first identifier treeid,the parameter outlabel in the second forwarding entry may be the secondlabel, and the parameter flag=popBIERexcluding may be the secondidentifier.

Step 504: The intermediate node obtains a second multicast data packetbased on the second forwarding entry and the first multicast datapacket, and sends the second multicast data packet, where the secondmulticast data packet includes the second label.

When the intermediate node receives the first multicast data packet andobtains the second forwarding entry, the intermediate node may processthe first multicast data packet based on the second forwarding entry, toobtain the second multicast data packet including the second label. Theintermediate node may send the second multicast data packet to thedownstream node of the intermediate node.

The second forwarding entry may further include an outbound interface.The outbound interface may be determined based on an identifier of thedownstream node of the intermediate node, and the outbound interface maybe the same as or different from an interface through which theintermediate node receives information sent by the downstream node ofthe intermediate node. Specifically, the intermediate node may delete,based on the second identifier in the second forwarding entry, the datain the BIER header of the first multicast data packet other than thefirst label, to obtain a data-deleted first multicast data packet. Theintermediate node replaces the first label included in the data-deletedfirst multicast data packet with the second label, to obtain the secondmulticast data packet. The intermediate node sends the second multicastdata packet to the downstream node of the intermediate node through theoutbound interface in the second forwarding entry. In this case, thefirst multicast data packet may be a packet that carries a BIER header,and the second multicast data packet may be a packet that carries a P2MPlabel but does not carry another parameter in the BIER header.

When the downstream node of the intermediate node is a leaf node, theleaf node may receive the second multicast data packet. The leaf nodemay obtain a third forwarding entry based on the first identifier. Thethird forwarding entry includes the first identifier and a fourthidentifier, and the fourth identifier is used to instruct to delete thesecond label. Therefore, the leaf node may delete the second label fromthe second multicast data packet based on the third identifier, toobtain the multicast IP packet. The leaf node reads a source IP and adestination IP (multicast group IP) in an IP header of the multicast IPpacket, finds, through matching, a local multicast forwarding entry,determines a local outbound interface based on the local multicastforwarding entry, and sends the multicast IP packet to the localoutbound interface. For example, the third forwarding entry may includea forwarding entry P2MP_NHLFE_Leaf represented as (treeid,flag=poplabel), the parameter treeid included in the forwarding entryP2MP_NHLFE_Leaf may be the first identifier, and the parameterflag=poplabel may be the fourth identifier. The multicast forwardingentry may include an MFIB (S, G, localmcastld), and the parameterlocalmcastld may be used to indicate the local outbound interface. For ameaning of the parameter flag=poplabel, refer to corresponding contentin the embodiment corresponding to FIG. 3 or FIG. 4 . For a method forobtaining, by the leaf node, the third forwarding entry and the fourthidentifier, refer to corresponding content in the embodimentcorresponding to FIG. 3 .

Specifically, referring to FIG. 6 , before the intermediate node obtainsthe second forwarding entry based on the first identifier (namely, step503), the method may further include steps 500 a and step 500 b. In FIG.6 , an example in which step 500 is performed before step 501 is usedfor description.

Step 500 a: The intermediate node receives a second label andconfiguration information that are sent by a downstream node in themulticast tree, where the configuration information is used to indicatethat the downstream node does not support to delete the data in the BIERheader other than the BIER label.

When the downstream node of the intermediate node does not support todelete the data in the BIER header other than the BIER label, thedownstream node may send the configuration information to theintermediate node, and send, to the intermediate node, the second labelallocated by the downstream node.

Step 500 b: The intermediate node generates the first forwarding entrybased on the second label and the configuration information, where thesecond identifier is an identifier obtained based on the configurationinformation.

The second identifier is an identifier obtained based on theconfiguration information. For a method for obtaining the secondidentifier, refer to the embodiment corresponding to FIG. 4 or FIG. 3 .When the intermediate node receives the configuration information, theintermediate node may obtain the second identifier based on theconfiguration information, and generate the second forwarding entrybased on the first identifier, the second label, and the secondidentifier. For example, the intermediate node may obtain an identifierflag=popBIERexcluding based on the configuration information, andgenerate the second forwarding entry based on the parameter treeid usedas the first identifier, a label label<by node 2> (the node 2 representsthe downstream node of the intermediate node) used as the second label,and the parameter flag=popBIERexcluding used as the second identifier.The second forwarding entry may be a forwarding entry P2MP_NHLFErepresented as (treeid, outinterface, outlabel, flag=popBIERexcluding).The parameter outlabel is label<by node 2>, namely, a label of thedownstream node of the intermediate node.

In a manner, before the intermediate node obtains the first forwardingentry based on the first label, the intermediate node may furthergenerate the first forwarding entry based on the first identifier andthe first identifier. For example, the intermediate node generates thefirst forwarding entry based on a label label<by node 1> (the node 1represents the intermediate node) used as the first label and theparameter treeid used as the first identifier. The first forwardingentry is a forwarding entry P2MP_ILM represented as (inlabel, treeid).The parameter inlabel is label<by node 1>, namely, a label of theintermediate node.

The multicast tree provided in this embodiment of this application mayinclude both a node that supports a BIER technology and a node that doesnot support the BIER technology. Specifically, processing may beperformed based on an operation corresponding to a flag in a forwardingentry of a node. Details are not described herein again. The node thatdoes not support the BIER technology is a node that does not support todelete the data in the BIER header other than the BIER label.

For ease of understanding, five scenarios shown in FIG. 7 to FIG. 11 areused as examples for description herein.

In FIG. 7 , a node F does not support to delete data in a BIER headerother than a BIER label, and another nodes supports to delete the datain the BIER header other than the BIER label. In this case, a node C maygenerate a corresponding forwarding entry based on information from F.The node C may process a received BIER packet in a corresponding mannerbased on a forwarding entry of the node C. For example, when forwardinga multicast data packet to the node F, the node C may delete data in aBIER header of the multicast data packet other than a BIER label. A BIERheader of a multicast data packet received by the node F includes onlythe BIER label. In addition, the node C may determine, based on whethera forwarding entry of the node C includes a parameter flag=P2MP, whetherto perform P2MP forwarding.

In FIG. 8 , the node C and the node F do not support to delete data in aBIER header other than a BIER label, and another node supports to deletethe data in the BIER header other than the BIER label. In this case, anode B may process a received BIER packet in the method performed by thenode C in FIG. 7 . A BIER header of a multicast data packet received bythe node C includes only the BIER label. A BIER header of a multicastdata packet forwarded by the node C to the node F and the node Dincludes only the BIER label. Because the node D supports a BIERtechnology, the BIER header of the multicast data packet sent by thenode C includes only the BIER label, and the node D may be configurednot to delete the data in the BIER header other than the BIER label. Inaddition, the node B and the node C may determine, based on whetherforwarding entries of the node B and the node C include a parameterflag=P2MP, whether to perform P2MP forwarding.

In FIG. 9 , the node B and the node F do not support to delete data in aBIER header other than a BIER label, and another node supports to deletethe data in the BIER header other than the BIER label. In this case, anode A may process a received BIER packet in the method performed by thenode C in FIG. 7 . Nodes C, E, and D may process the received multicastdata packet in a manner of the node D in FIG. 8 . In addition, the nodeB and the node C may determine, based on whether forwarding entries ofthe node B and the node C include a parameter flag=P2MP, whether toperform P2MP forwarding.

In FIG. 10 , a node C, a node F, and a node D do not support to deletedata in a BIER header other than a BIER label, and another node supportsto delete the data in the BIER header other than the BIER label. In thiscase, the node B may process a received BIER packet in the methodperformed by the node C in FIG. 7 . A BIER header of a multicast datapacket forwarded by the node C to the node F and the node D includesonly the BIER label. The node E may process the received multicast datapacket in a method performed by the node D in FIG. 8 . The node B andthe node C may determine, based on whether forwarding entries of thenode B and the node C include a parameter flag=P2MP, whether to performP2MP forwarding.

In FIG. 11 , a node B to a node F do not support to delete data in aBIER header other than a BIER label, and a node A supports to delete thedata in the BIER header other than the BIER label. In this case, thenode A may process a received BIER packet in the method performed by thenode C in FIG. 7 . The BIER packet is forwarded and processed in a P2MPmanner.

After a path between the node B and the node C in the multicast tree inFIG. 7 to FIG. 11 is replaced with a path between the node E and thenode C, the node E becomes a bud node. For a processing manner of thenode E, refer to the processing manners of the intermediate node and theleaf node. Details are not described herein again.

In this embodiment of this application, when the downstream node of theintermediate node does not support to delete the data in the BIER headerother than the BIER label, when forwarding a multicast data packet, theintermediate node may further delete the data in the BIER header of themulticast data packet other than the BIER label, so that the downstreamnode of the intermediate node can implement processing or forwarding onthe received multicast data packet. In this way, the BIER packet can beforwarded without upgrading hardware of the node, and hardware upgradingcosts are further reduced.

The solutions provided in the embodiments of this application are mainlydescribed from a perspective of interaction between network elements. Itmay be understood that network elements, for example, an intermediatenode and a leaf node, to implement the foregoing functions, includecorresponding hardware structures and/or software modules for performingthe functions. A person skilled in the art should easily be aware that,in combination with the examples described in the embodiments disclosedin this specification, units and algorithm steps can be implemented byhardware or a combination of hardware and computer software in thisapplication. Whether a function is performed by hardware or hardwaredriven by computer software depends on particular applications anddesign constraints of the technical solutions. A person skilled in theart may use different methods to implement the described functions foreach particular application, but it should not be considered that theimplementation goes beyond the scope of this application.

In the embodiments of this application, the intermediate node may bedivided into function modules based on the foregoing method examples.For example, each function module may be obtained through division basedon each corresponding function, or two or more functions may beintegrated into one module. The integrated module may be implemented ina form of hardware, or may be implemented in a form of a softwarefunction module. It should be noted that, in the embodiments of thisapplication, division into modules is an example, and is merely alogical function division. In actual implementation, another divisionmanner may be used. Descriptions are provided below by using an examplein which function modules are obtained through division based oncorresponding functions.

When an integrated unit is used, FIG. 12 is a possible schematicstructural diagram of the forwarding device used as an intermediate nodein the foregoing embodiments. The forwarding device used as anintermediate node supports to use P2MP to forward a BIER packet, andincludes a receiving unit 1201, an obtaining unit 1202, and a sendingunit 1203. The receiving unit 1201 is configured to support theforwarding device used as an intermediate node in performing step 301 inFIG. 3 or step 300 b and step 301 in FIG. 4 . The obtaining unit 1202 isconfigured to support the forwarding device used as an intermediate nodein performing step 302 and step 303 in FIG. 3 or FIG. 4 . The obtainingunit 1202 and the sending unit 1203 are further configured to supportthe forwarding device used as an intermediate node in performing step304 in FIG. 3 or FIG. 4 . Further, the forwarding device used as anintermediate node may further include a generation unit 1204. Thegeneration unit 1204 is configured to support the forwarding device usedas an intermediate node in performing step 300 a and step 300 c in FIG.4 . All related content of the steps in the foregoing method embodimentsmay be cited in function descriptions of the corresponding functionmodules. Details are not described herein again.

Based on hardware implementation, the obtaining unit 1202 and thegeneration unit 1204 in this application may be processors of theforwarding device used as an intermediate node, the receiving unit 1201may be a receiver of the forwarding device used as an intermediate node,the sending unit 1203 may be a transmitter of the forwarding device usedas an intermediate node, and the transmitter may be usually integratedwith the receiver and used as a transceiver. Specifically, thetransceiver may also be referred to as a communications interface.

FIG. 13 is a possible schematic diagram of a logical structure of theintermediate node in the foregoing embodiments according to anembodiment of this application. The intermediate node supports to useP2MP to forward a BIER packet, and includes a processor 1302 and acommunications interface 1303. The processor 1302 is configured tocontrol and manage an action of the forwarding device used as anintermediate node. For example, the processor 1302 is configured tosupport the forwarding device used as an intermediate node in performingsteps of the obtaining unit 1202 and the generation unit 1204, and/or isconfigured to perform another process of the technology described inthis specification. In addition, the forwarding device used as anintermediate node may further include a memory 1301 and a bus 1304. Theprocessor 1302, the communications interface 1303, and the memory 1301are connected to each other by using the bus 1304. The communicationsinterface 1303 is configured to support the forwarding device used as anintermediate node in communication. The memory 1301 is configured tostore program code and data of the forwarding device used as anintermediate node.

The processor 1302 may be a central processing unit, a general purposeprocessor, a digital signal processor, an application-specificintegrated circuit, a field programmable gate array or anotherprogrammable logic device, a transistor logic device, a hardwarecomponent, or any combination thereof. The processor 1302 may implementor execute various example logical blocks, modules, and circuitsdescribed with reference to content disclosed in this application.Alternatively, the processor may be a combination for implementing acomputing function, for example, a combination of one or moremicroprocessors, or a combination of a digital signal processor and amicroprocessor. The bus 1304 may be a peripheral component interconnect(PCI) bus, an extended industry standard architecture (EISA) bus, or thelike. The bus may be classified into an address bus, a data bus, acontrol bus, and the like. For ease of representation, only one thickline is used to represent the bus in FIG. 13 , but this does not meanthat there is only one bus or only one type of bus.

When an integrated unit is used, FIG. 14 is a possible schematicstructural diagram of the forwarding device used as an intermediate nodein the foregoing embodiments. The forwarding device used as anintermediate node supports to delete data in a BIER header other than aBIER label, and includes a receiving unit 1401, an obtaining unit 1402,and a sending unit 1403. The receiving unit 1401 is configured tosupport the forwarding device used as an intermediate node in performingstep 501 in FIG. 5 or step 500 a and step 501 in FIG. 6 . The obtainingunit 1402 is configured to support the forwarding device used as anintermediate node in performing step 502 and step 503 in FIG. 5 or FIG.6 . The obtaining unit 1402 and the sending unit 1403 are furtherconfigured to support the forwarding device used as an intermediate nodein performing step 504 in FIG. 5 or FIG. 6 . Further, the forwardingdevice used as an intermediate node further includes a generation unit1404, configured to perform step 500 b in FIG. 6 . All related contentof the steps in the foregoing method embodiments may be cited infunction descriptions of the corresponding function modules. Details arenot described herein again.

Based on hardware implementation, the obtaining unit 1402 and thegeneration unit 1404 in this application may be processors of theforwarding device used as an intermediate node, the receiving unit 1401may be a receiver of the forwarding device used as an intermediate node,the sending unit 1403 may be a transmitter of the forwarding device usedas an intermediate node, and the transmitter may be usually integratedwith the receiver and used as a transceiver. Specifically, thetransceiver may also be referred to as a communications interface.

FIG. 15 is a possible schematic diagram of a logical structure of theforwarding device used as an intermediate node in the foregoingembodiments according to an embodiment of this application. Theforwarding device used as an intermediate node supports to delete datain a BIER header other than a BIER label, and includes a processor 1502and a communications interface 1503. The processor 1502 is configured tocontrol and manage an action of the forwarding device used as anintermediate node. For example, the processor 1502 is configured toperform steps of the obtaining unit 1402 and the generation unit 1404,and/or is configured to perform another process of the technologydescribed in this specification. In addition, the forwarding device usedas an intermediate node may further include a memory 1501 and a bus1504. The processor 1502, the communications interface 1503, and thememory 1501 are connected to each other by using the bus 1504. Thecommunications interface 1503 is configured to support the forwardingdevice used as an intermediate node in communication. The memory 1501 isconfigured to store program code and data of the forwarding device usedas an intermediate node.

The processor 1502 may be a central processing unit, a general purposeprocessor, a digital signal processor, an application-specificintegrated circuit, a field programmable gate array or anotherprogrammable logic device, a transistor logic device, a hardwarecomponent, or any combination thereof. The processor 1502 may implementor execute various example logical blocks, modules, and circuitsdescribed with reference to content disclosed in this application.Alternatively, the processor may be a combination for implementing acomputing function, for example, a combination of one or moremicroprocessors, or a combination of a digital signal processor and amicroprocessor. The bus 1504 may be a peripheral component interconnect(PCI) bus, an extended industry standard architecture (EISA) bus, or thelike. The bus may be classified into an address bus, a data bus, acontrol bus, and the like. For ease of representation, only one thickline is used to represent the bus in FIG. 15 , but this does not meanthat there is only one bus or only one type of bus.

In another embodiment of this application, a readable storage medium isfurther provided. The readable storage medium stores a computerexecutable instruction. When a device (which may be a single-chipmicrocomputer, a chip, or the like) or a processor performs the steps inthe multicast data packet processing method provided in FIG. 3 or FIG. 4, the foregoing storage medium may include any medium that can storeprogram code, such as a USB flash drive, a removable hard disk, aread-only memory, a random access memory, a magnetic disk, or an opticaldisc.

In another embodiment of this application, a readable storage medium isfurther provided. The readable storage medium stores a computerexecutable instruction. When a device (which may be a single-chipmicrocomputer, a chip, or the like) or a processor performs the steps inthe multicast data packet processing method provided in FIG. 5 or FIG. 6, the foregoing storage medium may include any medium that can storeprogram code, such as a USB flash drive, a removable hard disk, aread-only memory, a random access memory, a magnetic disk, or an opticaldisc.

In another embodiment of this application, a computer program product isfurther provided. The computer program product includes a computerexecutable instruction, and the computer executable instruction isstored in a computer readable storage medium. At least one processor ofa device may read the computer executable instruction from the computerreadable storage medium, and when the at least one processor executesthe computer executable instruction, the device implements the steps inthe multicast data packet processing method provided in FIG. 3 or FIG. 4.

In another embodiment of this application, a computer program product isfurther provided. The computer program product includes a computerexecutable instruction, and the computer executable instruction isstored in a computer readable storage medium. At least one processor ofa device may read the computer executable instruction from the computerreadable storage medium, and when the at least one processor executesthe computer executable instruction, the device implements the steps inthe multicast data packet processing method provided in FIG. 5 or FIG. 6.

In the embodiments of this application, if the forwarding device used asan intermediate node cannot identify and process a bit string in a BIERheader, but supports to use P2MP to forward a BIER packet, when theforwarding device used as an intermediate node receives a firstmulticast data packet and obtains a first forwarding entry and a secondforwarding entry, the forwarding device used as an intermediate node mayprocess the first multicast data packet based on the second forwardingentry and a second identifier that is in the first forwarding entry andthat is used to instruct to perform P2MP forwarding on the packet, toobtain a second multicast data packet, and does not need to read oranalyze the BIER header of the first multicast data packet duringprocessing, so that the BIER packet can be forwarded without upgradinghardware of the node, thereby reducing hardware upgrading costs. Inaddition, when a downstream node of the forwarding device used as anintermediate node does not support to delete data in the BIER headerother than a BIER label, when forwarding a multicast data packet, theforwarding device used as an intermediate node may further delete thedata in the BIER header of the multicast data packet other than the BIERlabel, so that a downstream node of the intermediate node can implementprocessing or forwarding on the received multicast data packet. In thisway, the BIER packet can be forwarded without upgrading hardware of thenode, and hardware upgrading costs are further reduced.

Finally, it should be noted that the foregoing descriptions are merelyspecific implementations of this application, but are not intended tolimit the protection scope of this application. Any variation orreplacement within the technical scope disclosed in this applicationshall fall within the protection scope of this application. Therefore,the protection scope of this application shall be subject to theprotection scope of the claims.

What is claimed is:
 1. A multicast packet processing method, comprising:receiving, by an intermediate node, a first Bit Index ExplicitReplication (BIER) packet, wherein the first BIER packet comprises aBIER header, and the BIER header comprises a first label, and a firstparameter other than the first label; obtaining, by the intermediatenode and according to the first label, a second label corresponding to amulticast tree comprising the intermediate node; obtaining, by theintermediate node, a second BIER packet according to the second labeland the first BIER packet; and sending, by the intermediate node, thesecond BIER packet, wherein the second BIER packet comprises the secondlabel; and the obtaining the second BIER packet comprises deleting thefirst parameter.
 2. The method according to claim 1, wherein theobtaining the second label comprises: obtaining, by the intermediatenode and according to the first label, a first identifier correspondingto the first label and identifying the multicast tree; and obtaining, bythe intermediate node and according to the first identifier the secondlabel corresponding to the first identifier.
 3. The method according toclaim 1, wherein the obtaining the second BIER packet comprises:obtaining, by the intermediate node and according to the first label, asecond identifier and an outbound interface which correspond to thefirst label, wherein the second identifier instructs the intermediatenode to perform point-to-multipoint (P2MP) forwarding; and replacing, bythe intermediate node and according to the second identifier, the firstlabel in the first BIER packet with the second label, to obtain thesecond BIER packet; and the sending the second BIER packet comprises:sending, by the intermediate node, the second BIER packet by using theoutbound interface.
 4. The method according to claim 3, furthercomprising: obtaining, by the intermediate node and according to firstconfiguration information and the first label, the second identifiercorresponding to the first label, wherein the first configurationinformation indicates that the intermediate node is configured toforward a BIER packet by using P2MP, and the second identifier is anidentifier obtained according to the first configuration information. 5.The method according to claim 1, wherein the obtaining the second BIERpacket comprises: obtaining, by the intermediate node and according tothe first label, a second identifier and an outbound interface whichcorrespond to the first label, wherein the second identifier instructsthe intermediate node to perform point-to-multipoint (P2MP) forwarding;obtaining, by the intermediate node and according to the second label, athird identifier corresponding to the second label, wherein the thirdidentifier instructs the intermediate node to delete a parameter otherthan a BIER label from a BIER header; replacing, by the intermediatenode and according to the second identifier, the first label in thefirst BIER packet with the second label, to obtain a label-replacedfirst BIER packet; and the deleting the first parameter comprises:deleting, by the intermediate node and according to the thirdidentifier, the first parameter, without deleting the second label, in aBIER header of the label-replaced first BIER packet, to obtain thesecond BIER packet; and the sending the second BIER packet comprises:sending, by the intermediate node, the second BIER packet by using theoutbound interface.
 6. The method according to claim 5, furthercomprising: obtaining, by the intermediate node and according to firstconfiguration information and the first label, the second identifiercorresponding to the first label, wherein the first configurationinformation indicates that the intermediate node is configured toforward a BIER packet by using P2MP, and the second identifier is anidentifier obtained according to the first configuration information;receiving, by the intermediate node, the second label and secondconfiguration information from a downstream node of the multicast tree,wherein the second configuration information indicates that thedownstream node is not configured to delete a parameter other than aBIER label in a BIER header; and obtaining, by the intermediate node andaccording to the second label and the second configuration information,the third identifier corresponding to the second label, wherein thethird identifier is an identifier obtained according to the secondconfiguration information.
 7. The method according to claim 1, whereinthe obtaining the second BIER packet comprises: obtaining, by theintermediate node and according to the first label, a second identifierand an outbound interface which correspond to the first label, whereinthe second identifier instructs the intermediate node to performpoint-to-multipoint (P2MP) forwarding; obtaining, by the intermediatenode and according to the second label, a third identifier correspondingto the second label, wherein the third identifier instructs theintermediate node to delete a parameter other than a BIER label from aBIER header; the deleting the first parameter comprises: deleting, bythe intermediate node and according to the third identifier, the firstparameter, without deleting the first label in the BIER header of thefirst BIER packet, to obtain a parameter-deleted first BIER packet; andreplacing, by the intermediate node and according to the secondidentifier, the first label in the parameter-deleted first BIER packetwith the second label, to obtain the second BIER packet; and the sendingthe second BIER packet comprises: sending, by the intermediate node, thesecond BIER packet by using the outbound interface.
 8. The methodaccording to claim 7, further comprising: obtaining, by the intermediatenode and according to first configuration information and the firstlabel, the second identifier corresponding to the first label, whereinthe first configuration information indicates that the intermediate nodeis configured to forward a BIER packet by using P2MP, and the secondidentifier is an identifier obtained according to the firstconfiguration information; receiving, by the intermediate node, thesecond label and second configuration information from a downstream nodeof the multicast tree, wherein the second configuration informationindicates that the downstream node is not configured to delete aparameter other than a BIER label in a BIER header; and obtaining, bythe intermediate node and according to the second label and the secondconfiguration information, the third identifier corresponding to thesecond label, wherein the third identifier is an identifier obtainedaccording to the second configuration information.
 9. A forwardingdevice, comprising: a memory storing instructions; and a processorcoupled to the memory to execute the instructions, wherein the executedinstructions instruct the processor to: receive a first Bit IndexExplicit Replication (BIER) packet, wherein the first BIER packetcomprises a BIER header, and the BIER header comprises a first label,and a first parameter other than the first label; obtain, according tothe first label, a second label corresponding to a multicast treecomprising the forwarding device; obtain a second BIER packet accordingto the second label and the first BIER packet and by deleting the firstparameter, wherein the second BIER packet comprises the second label;and send the second BIER packet.
 10. The forwarding device according toclaim 9, wherein the executed instructions instruct the processor to:obtain, according to the first label, a first identifier correspondingto the first label and identifying the multicast tree; and obtain,according to the first identifier the second label corresponding to thefirst identifier.
 11. The forwarding device according to claim 9 whereinthe executed instructions instruct the processor to: obtain, accordingto the first label, a second identifier and an outbound interface whichcorrespond to the first label, wherein the second identifier instructsthe forwarding device to perform point-to-multipoint (P2MP) forwarding;replace, according to the second identifier, the first label in thefirst BIER packet with the second label, to obtain the second BIERpacket; and send the second BIER packet by using the outbound interface.12. The forwarding device according to claim 11, wherein the executedinstructions instruct the processor to: obtain, according to firstconfiguration information and the first label, the second identifiercorresponding to the first label, wherein the first configurationinformation indicates that the forwarding device is configured toforward a BIER packet by using P2MP, and the second identifier is anidentifier obtained according to the first configuration information.13. The forwarding device according to claim 9, wherein the executedinstructions instruct the processor to: obtain, according to the firstlabel, a second identifier and an outbound interface which correspond tothe first label, wherein the second identifier instructs the forwardingdevice to perform point-to-multipoint (P2MP) forwarding; obtain,according to the second label, a third identifier corresponding to thesecond label, wherein the third identifier instructs the forwardingdevice to delete a parameter other than a BIER label from a BIER header;replace, according to the second identifier, the first label in thefirst BIER packet with the second label, to obtain a label-replacedfirst BIER packet; delete, according to the third identifier, the firstparameter, without deleting the second label in a BIER header of thelabel-replaced first BIER packet, to obtain the second BIER packet; andsend the second BIER packet by using the outbound interface.
 14. Theforwarding device according to claim 13, wherein the executedinstructions instruct the processor to: obtain, according to firstconfiguration information and the first label, the a second identifiercorresponding to the first label, wherein the first configurationinformation indicates that the forwarding device is configured toforward a BIER packet by using P2MP, and the second identifier is anidentifier obtained according to the first configuration information;receive the second label and second configuration information from adownstream node of the multicast tree, wherein the second configurationinformation indicates that the downstream node is not configured todelete a parameter other than a BIER label in a BIER header; and obtain,according to the second label and the second configuration information,the third identifier corresponding to the second label, wherein thethird identifier is an identifier obtained according to the secondconfiguration information.
 15. The forwarding device according to claim9, wherein the executed instructions instruct the processor: obtain,according to the first label, a second identifier and an outboundinterface which correspond to the first label, wherein the secondidentifier instructs the forwarding device to performpoint-to-multipoint (P2MP) forwarding; obtain, according to the secondlabel, a third identifier corresponding to the second label, wherein thethird identifier instructs the forwarding device to delete a parameterother than a BIER label from a BIER header; delete, according to thethird identifier, the first parameter, without deleting the first labelin the BIER header of the first BIER packet, to obtain aparameter-deleted first BIER packet; replace, according to the secondidentifier, the first label in the parameter-deleted first BIER packetwith the second label, to obtain the second BIER packet; and send thesecond BIER packet by using the outbound interface.
 16. The forwardingdevice according to claim 15, wherein the executed instructions instructthe processor to: obtain, according to first configuration informationand the first label, a second identifier corresponding to the firstlabel, wherein the first configuration information indicates that theforwarding device is configured to forward a BIER packet by using P2MP,and the second identifier is an identifier obtained according to thefirst configuration information; receive the second label and secondconfiguration information from a downstream node of the multicast tree,wherein the second configuration information indicates that thedownstream node is not configured to delete a parameter other than aBIER label in a BIER header; and obtain, according to the second labeland the second configuration information, the third identifiercorresponding to the second label, wherein the third identifier is anidentifier obtained according to the second configuration information.